By enabling collections you are choosing to have all the products under the collection to have the Make an Offer feature in the product pages. You will also enter the accept percentage (maximum discount percentage allowed) for all the products under this collection.
In case you have an individual product(of this collection) too is enabled with it’s own Accept Price, then that product’s Accept Price is given priority.
Open the app at Shopify admin apps section.
1. Click on Manage Collections button to enable the collections
2. Enter your Accept Percentage (maximum discount percentage allowed) for each collection & Save. This is the discount percentage you are guaranteed to get and the negotiation will never close below this discount. This will not be revealed to the shopper.
All products under the collection should now have Make an Offer button with the Accept Percentage (unrevealed maximum allowed discount) you entered.
If the Make an Offer button is not showing up, please check out this trouble shooting article.