Could not find a version of package ecomteck/module-pdfgenerator matching your minimum-stability (stable). Require it with an explicit version constraint allowing its desired stability.

[mateuszrusiecki]

You need to add a tag

[ecomteck]

Dear,
Please try to setup module first version at here: https://github.com/ecomteck/module-pdfgenerator/releases/tag/1.0.0