SAAS to SAAS multi tenant automatic create account

Hello, I'm looking for a freelancer who can help me. I have a code service platform ready, I would like to transform it into Saas and natively integrate some external systems. Long-term project.

-transform into saas
-change the front-end, make it more modern and with ui/ux
-integrate channels like whatsapp cloud api
-make continuous improvements to codes