I think the key question is whether you’re trying to get the description of the parent part or one of the children material parts. If you want the parent part, you should be able to link the Part table to the PartMtl and link by: PartMtl.Company = Part.Company And PartMtl.PartNum = Part.PartNum.
If you want the part description of the mtl parts, you need the following link instead: PartMtl.Company = Part.Company And PartMtl.MtlPartNum = Part.PartNum.
Another question is do you want part description for the parent part AND the child part?
If you do want both descriptions, you will need to join the part table twice. So Part table as the parent table linked to the child table PartMtl. .Then join Part again as an alias to the PartMtl table. The description for the child would be the Part(Alias).Description.
I would like to thank both @kalbee and @djo for their answers. Kevin’s answer put me on the path but Doug’s gave me a shortcut I didn’t even think about, that’s why I marked his answer over Kevin.
I appreciate it when people can take time out of their day to help someone who doesn’t know it well enough but hopefully someday will be able to pass it on like these excellent people.