I own a website www.cambizzle.com and want to use the collections widget to collect payments via MOMO for users who have posted their ads on the website. I am not the developer but really need help because my developer has added a payment screen on my website and one of the mandatory fields to enter is Momo user id (see screenshot). the pay now button results in bad request sent.

I do not understand what a user of my website who wants to make payments will input as Momo user id. the sites i have used Momo with e.g ULiF and all i need to do as a user is input my Momo number and funds will be deducted for payments.

Will really appreciate your help.