There is a test before this one that OP would have completed. This tests for the proficiency of the unit you have just completed and is necessary to then advance onto the more advanced levels.
The test in the picture is an additional one for some kind of busuu certificate, I don’t know if it counts as official accreditation but I doubt it very much.
Not paying doesn’t hinder your progress at all and you miss nothing from not doing this silly certificate test at all other than like you say so e-peen waving I guess?
I learn Spanish to speak it with my gf and busuu has been amazing when compared to shit like Duolingo that doesn’t teach you anything usable at all so this shade being thrown based on some stupid certificate is totally unjustified.