Multi-use payment link not showing when I want create a link

A multipayment link is exclusive to QuickBooks Desktop (QBDT) and QuickBooks Online (QBO), @Sulingexpress. Thus, it's why you're unable to utilize the feature in QuickBooks Solopreneur. We'll provide more details below and a workaround to help handle customer payments. 
 
Since the option isn't available on your subscription, you can consider generating a link for your invoices and manually sending them to your customers. This way, they can use the link and pay their dues seamlessly. 

If you're dealing with multiple customers, consider upgrading your current subscription to QBO. With this, you can streamline the process and manage customer payments more efficiently. Refer to this handy article for more details: Learn what changes when you upgrade from QuickBooks Solopreneur to other QuickBooks Online editions.

On the other hand, here's an article to help you categorize transactions in QuickBooks: Schedule C and expense categories in QuickBooks Solopreneur and QuickBooks Self-Employed.

Our team highly encourages you to utilize the comment section if you require further assistance handling customer payments or need a helping hand with QuickBooks-related concerns. We'll do our best to get back to you as soon as possible and answer your inquiries, @sulingexpress.