It has been over 7 months now and they do not reply to my emails and my funds are still locked

it's most likely because you haven't given them the proof of funds(that they deem valid) that they have been asking from you seven months ago. at this point, they have probably deemed the case closed as the gambler failed to provide the documents that they asked from you, that's why they aren't responding to your emails.
I do small tasks like writing, and designing and get crypto for that and I used that money to deposit and play. I don't understand how to provide the proof of funds. Assume you use your signature campaign earnings to gamble and it's not a valid proof of fund for them, then you will forfeit your money to them?
don't get me wrong, I too find their "acceptable documents for proof of funds" a little ridiculous, but then again, those rules are on their ToS and you did agree to it when you registered an account on their gambling site and they expect you to follow it. it is a shitty situation that I think you can't really win.
They show people winning million dollars and they are scamming me for $300. Maybe those promos and social media posts are fake and big fraud is going on.