So while i have had friends and exes that have played for years, and decades around me, I have never personally played any table top rpg's. for the last two months or so i have been consuming critical role, legend of vox machina,  campaign 2, exandria unlimited and trying to get understand this site and the source books. I have only been an account holder on dnd beyond for the last couple of months. I have bought the 2024 players handbook, mordenkainen's monsters of the monsterverse, tasha's cauldron of everything, xanathar's guide to everything, and have only made a few characters.  A sea elf ranger sailor which i think i will turn beast master, a wood elf druid guide which I think I will turn circle of the moon, a silver dragonborn wayfarer with an unknown subclass as of yet and an aasimar fighter soldier with an unknown subclass as of yet as well. For the last two months I have been trying to take in all of the books and what i have seen from the shows and get them down pat. Now, right now i will not have any in person type games near me, but to be future prepared i bought a handful of sets of dice, and a dice bag. I have not purchased any mini's yet.  I will be moving in a few months, so i have been considering using an online service. While I think I am starting to get a decent handle on the rules in the 4 books I have purchased already, I do not understand yet how the online elements work for dnd beyond and the subscription and now I see the sigil service is closing. I tried to read through the initial post and a few others, but I'm not sure I'm quite understanding how the maps virtual table top stuff, the sigil table top stuff, the subscription service all relates to having an account and what is the best platform to use, to use the characters I spent a long time trying to craft on here?

any advice?

Greetings Morgan! 

First, I will say you do not need to buy anything to play D&D and fully enjoy it, and minis are absolutely not required to play (I rarely use mine anymore, honestly). You have likely already bought more than you need right now. 

Sigil is a 3d virtual table top that allows the creation of maps and the use of digital minis and dice within the platform. It requires at least a medium performance computer system to use. Since it has officially been announced that WotC will be ending service next year, I would not recommend relying too heavily on it if you can run it. If your computer can handle the demands, it is still available for download and free use here. The downside is that everyone playing has to meet the minimum system requirements and that is apparently a big ask for the D&D community. 

Maps can be found here, and is hosted by the Dungeon Master through the browswer and the players access it through the Launch Portal from the campaign page. It is decent as far as 2D virtual tabletops go, and easily incorporates your characters into the maps. I like using it because as a DM, it gives me a reasonable amount of tools and the integration with the characters and monsters works really well. 

Subscription information can be found here, but the short version is that the subscription gives the ability to make unlimited characters, early access to new tools (when the site has them), and monthly vanity items like backdrops and digital dice. Master Tier also allows Homebrew integration into Maps and allows the sharing of purchased content with other players. You don't need a subscription service to play. It just gets you some useful extras if you are a DM and some vanity items. If you like vanity items (I do), great. But I would recommend that you play a few times before deciding to pay for anything on this game.

As far as what is the best platform, that is not an easy question to answer. DDB certainly allows you to use many tools here that integrate perfectly with your characters, but whether it is best is not something that other people will be able to answer for you. I would say you have all you need here to play right now. You just need to find a group. For that, I recommend you look at this forum.

Welcome to the site and hopefully, welcome to the game. If it happens to be your thing, you will have a lifetime of fun playing it. 

You can ignore Sigil in it's entirety, since WotC just canceled the project. 

There's plenty of free VTT's out there though. I use roll20 for my online campaigns and I've enjoyed it and never spent a cent.