Tips for Beginners:
Glass material is not transparent after upgrade to HDRP?
Just switch it to opaque, after that to transparent again
Try import Complete Project HDRP?
Install all dependencies and settings for it.
Not a mobile device project?
Don't forget switch project to correct color space - Linear (edit > project settings > player > other settings)
Can't download / import asset from Store?
Nothing is easier: just Restart Unity Editor
Need construct within modular asset?
Modular asset is grid based? Hold Ctrl and drag prefab for construct;
Asset is non grid based? Hold V and drag to vertex.
All lights shine dimly after upgrade to HDRP?
Just increase light sources intensity