Not all adult is the same. There are big differences between being a performer (OnlyFans or similar), a production company, and a distribution company.
YourSafe, Paxum, and CosmoPayments are some of the most popular options for performers. Sometimes EMIs with a high risk appetite will take it if you make a strong business case.
And sometimes it's better to structure the business such that the EMI can believably onboard you without necessarily knowing that there's adult involvement. This needs to be done carefully so at to not accidentally end up committing fraud or money laundering.