RDP problem with second user

**Data Source=SOMA-PC\SQLEXPRESS; User Id=sa; Password=sambapos; Database=SambaPOS; **
Login failed for user ‘sa’.
When I remove user SA it works on the main account. In MSSMS I added the user MYPC\Tablet and I can login, but I when I try to open the POS screen it says no valid licence.
I followed steps 3 and 4 from this guide but SA user still doesn’t work. Common Database Connection Issues - How to resolve them

The SQL processes are running.