There are two ways to purchase subscriptions from the member account, so two different URLs:
Either via a direct payment link from the contract in the back office sent by the manager:
Click on "Products" > "Contracts" > Select the contract in question > Click on "Copy link to payment page".
Paste the link on a new web page.
(This is an example)
The member goes directly to the shopping cart to buy the subscription.
Either via the marketplace from the "Subscriptions" tab:
Select "Settings" > Click on "Marketplace settings"> Click on "Access the customer marketplace (you will be logged out).
Once you have arrived at your clients' visuals, click on "Subscription".
The URL is: https://backoffice.bsport.io/m/Ikigai%20Studio%20/223/subscription/?tabSelected=7&selected=3344
(This is just an example)