I was able to link my Open work Permit following this steps:
You can also link through your online account via Sign-in Partner or GCkey (whichever you already have)
TO LINK OPEN WORK PERMIT (This is what I did, hope this works for you too)
Category: Temporary Resident
Sub-category: Work Permit and Extension
➡︎ Use UCI and Family Name
➡︎ Do NOT enter anything in the town/city of birth and Country
Enter Passport Information:
↳ Passport Number
↳ Country of Issue
↳ Issue Date and Expiry Date
Details of intended work in Canada
Type of Work Permit: Open (Initial Application or Extension
Personal Information:
↳ Current Country of Residence: Canada
↳ Current Marital Status
↳ Which situation applies to the applicant: Applied for permanent residence as a spouse or common-law partner in Canada