Julie here from Shopify Support.
When you were notified that your account was on hold, did you receive an email or a prompt in your admin to upload any documents?
Oftentimes, our Shopify Payments team will reach out via email when these instances occur. They may also request documents from merchants as part of a general underwriting process. Our Shopify Payments FAQ also includes some information about payouts being on hold, so I suggest checking that out!
Without being able to access your account here on my end, it's quite difficult to discern why your Shopify Payments account is on hold. For that reason, I suggest double-checking your email and your Shopify admin to see if there is any information about the hold and whether there are any required actions you need to take.
For any questions about your Shopify Payments account, it's best that you contact Shopify Support directly. Our Support team will be able to authenticate and access your account, and discuss this further with you. Alternatively, if you received an email about the hold from our Shopify Payments team, then you can respond to that email and they will be able to offer some insight.
Lastly, I wanted to mention that you should be able to proceed with launching your store while your payouts are on hold; processing payments should still be possible, but the payouts themselves will be on hold. Once you get in touch with Support, however, they'll be able to advise you on next steps.
I hope this leads you in the right direction!