Type these (in every addon you want to install) and you will by-pass it
Main Item Purchace code: 8E11-A7FB-E2A4-4F2F
Addon Purchace code: 0532a0a1-192a-42e1-95e2-0ff1012449dc
p.s. the addon "backup-restore-system-addon-1.8" is shoing error 500, I and I'm not install it, until I 'll figure out what's the problem