Based on your description, I understand that in the SharePoint Designer, when you want to create a lookup column in the list, you cannot get created columns in the document library.
1.Only following column types are supported in the lookup column.
- Single line of text
- Choice (single value)
- Number
- Currency
- Date and Time
- Lookup (single value)
- Person (single value)
2.After you have created columns in the document library, you should click Save in the SharePoint Designer. Then try to create a lookup column in the list.
3.Make sure you have enough permission for the list and document library.
4.Please try to directly create lookup column into SharePoint list in the browser, compare the result.
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