The marketplace and its supply side
PartnerStack's network brings partners to you, and a migration does not bring them with it. Referly has its own marketplace, but it is a separate licence rather than something the move includes, and it is a different network with different people in it. If a meaningful share of your partners came from theirs, price that honestly before you decide.
Partner types and tiers
Affiliate, reseller and agency partner structures have no equivalent object. Referly models this with affiliate groups, commission plans and milestones, which cover a lot of the same ground in a flatter shape. Rebuilding it is the bulk of the one to two weeks.
Managed-partner workflows
Challenges, learning modules, MDF management and the workflow tooling around managed partners do not export and have no import target.
Commission structures
Rebuilt by hand, as on every migration from every tool.
The historic click log
Not importable from any tool. Click and conversion-rate charts start on cutover day.
Partners and their details
Names, emails, payout emails and status, over the Vendor API.
Referral links and codes
The code survives the move; the domain it points at changes.
Customers, sales and commissions
With their original dates, so the history you built on PartnerStack is still the history you report on.
Paid payouts
Sales you import can carry their paid status, so nobody is paid twice. The payout records themselves stay behind.
Unpaid commissions
Import them marked unpaid and pay from Referly, or pay them out of PartnerStack first.
Commission structures are rebuilt by hand on every migration, from every tool, including this one. On PartnerStack that is the smallest item on the list rather than the largest, which is the clearest signal that this migration is different in kind from its siblings.
program into 
Rewardful
FirstPromoter
Tolt
