Can a Lycan Blood Hunter in their hybrid form concentrate on spells?  The description doesn't say that it prevents concentration (as the description of the Barbarian rage does).  However, it certainly implies that the transformed lycan is using its concentration to tamp down the bloodlust, stating:  "If you are under an effect that prevents you from concentrating (like the Barbarian’s rage feature), you automatically fail this saving throw."

Thoughts?  I suppose the universe of possible interpretations is:

• The description doesn't say you can't concentrate on spells in hybrid form, so you can;
• The description implies that you are already concentrating on resisting the bloodlust, so you can't; or
• you can concentrate on a spell, but if you are doing so, you automatically fail the bloodlust saving throw because the spell concentration prevents you from concentrating on anything else.

The short answer is that the rules don't specify one way or another.

I don't look at Bloodlust as something that must constantly be kept in check. I think of it as something that can blow up and potentially overwhelm a lycan when they take damage. Under that interpretation, there would be no issue with concentrating on spells. The lycan in my campaign doesn't cast spells, but I think you could make the logical argument that if a lycan fails their bloodlust check, then the rage would overwhelm them and that could break their spell concentration. That would be a house rule, but a plausible one. Under those circumstances, I would always roll the bloodlust check before the concentration check. That essentially doubles the chance of losing concentration.

I like your rule.  I guess I was reading the "you automatically fail if you can't concentrate" as implying that concentration was necessary to hold the bloodlust in check.  But, I think your rule covers things pretty well, and doubling the chance of losing concentration balances the abilities nicely.