Rigging custom mesh to GASP properly

I spent nearly two days trying to properly rig my custom mesh in blender, and retargeting it to GASP, I’m exhausted and don’t know what I’m doing wrong, I even bought the Auto Rig Pro or tried to use Game Rig Tool.

I tried building the skeleton myself, I’m clearly missing something and forgot I’m a rookie, the feet of the character is clipping the floor when I start walking, in idle it’s fine but not sticking to the ground very well, I’ve thought of maybe that’s because the mesh is more bulkier than standard humanoid but the bones are aligned properly so i don’t think it’s the case.

When importing the skeleton from the blender addons which supposed to be identical to the UE Manny, I tried retargeting that, instead of choosing the SK_Mannequin in the import settings. Which shouldn’t do any difference because they are the same skeletons, and I even get no error importing it, so no missing bones, there are ik bones and nothing is missing. I could provide the skeleton if anyone is requesting but heres a video showing the problem with the mesh: