mixamo not importing colors

your model already has some Mixamo bones so the rigging step will be autoskipped but that gun is not desgined well

your base model is A and T would have been better but its the gun itself that creates issues... as a workflow I would start with the guy [unarmed], download all the animations you want to use [T pose is the most important one] and then use the Blender control rig to attach the Gun or Iclone [whatever] because that attach step breaks things it should always go last

Q are the colours you had in this model texture based?

Mixamo doesn't show colour because there is no colour stored in that file

a side issue is the file type is 2 which most 3D software will not read without errors... use wavefront/ Obj instead then you can convert that to standard Fbx at time of upload or just include the textures as a zip

There is a Mixamo forum here, and this question most properly belongs in it. Let me move it for you.

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