PayPal Adaptive Plugin Issues

Right so iv set this all up. Created the app got the app ID got the credentials enabled it. I posted an as with my admin account then logged in on another account and it all worked perfect. Then I got someone else to post an ad and I tried to buy it and wouldn’t wprk all I keep getting is User is not allowed to perform this action Could someone please help me with this I cannot seem to figure out why it will not work

Thanks