I received the same bonus for the migration which was a nice bonus although I lost it all quite fast.
Coming up to the login issue, I think it is because of the migration, high likely Playbetr wont be accessible anymore in the near future as they have informed players to do migration process to Betcoin.
In case anyone has some balance in Playbetr account and have not done the migration process, it is better to contact betcoin support in order to do migration and maybe transfer the available balance in Playbetr to Betcoin.