Promotion problem

Hello,

I want to use the €5 coupon I was given by Instagram before it expires, but it won't let me boost anything. In the app, once I select ''Boost post'', the ''Next'' button does not work and it stays there. From Meta Business Suite, I select ''Promote an Instagram post'' and it lets me configure everything, but at the end the ''Promote with credit'' button doesn't work either.

How can I solve this? Thank you.