What do you mean? This site has the information for all officially published WOTC 5th edition classes. If you are looking for a different edition then you won't see them. If you mean you aren't seeing the sub-classes then you need to make a purchase to have access to the ones that aren't listed in the free SRD or basic rules, both available from the WOTC website.
Are we limited to the classes shown in 5e?
Yes, all the classes published in the physical books. Some of the archetypes are free, others need a purchase.
I only see the one listed in 5th edition
Yes, DDB is only for 5th edition D&D official content.
For some reason I thought this includes classes from all editions
I purchased the 297.00 level which should have gotten me everything up to this point
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Or so I thought