I'm sorry to hear you're having trouble processing the payment for your store. Regretfully, we have limited information when it comes to why your credit card was declined as the bank only provides us with a short error. It can range from "insufficient funds" to "Do not honour." Regardless of the error, we're unable to bypass it and it would require speaking with your bank to determine why the card was declined. Keep in mind that our systems charge in USD, so if you're using an international card, then you'll want to ensure you have funds available to cover the conversion, plus any additional fees your bank may charge for processing the conversion. You'll also want to ensure that you're using a supported credit card which is a card issued by a bank with a line of credit, and not a visa/MasterCard branded debit card. As for Paypal, if you're seeing an error when trying to process a payment then you will want to reach out to Paypal support as they'll be able to troubleshoot that further.
If you're still having trouble after checking your payment type and/or speaking with Paypal let me know!
When using Shopify Payments, there will be standard reviews to validate the business and to ensure that your business is adhering to the Shopify Payments Terms of Service. If you've been prompted to upload your documents via your admin then you'll want to do so as soon as possible. Once you've submitted your documents it can typically take between 1-3 business days to review the documents you've provided. If there any issues then our teams will request further information; however, if not, then the hold will be removed, and payouts will resume as normal. Are you getting an error when trying to submit the documents, or is the issue that you've submitted them but you're still getting emails to submit documents?