If you have just recently opened your new Stripe account and your customers are struggling to complete a payment, it is very likely that you simply need to provide more information to Stripe.
Please check whether the following message appears in the payment step:
"This account cannot currently make live charges. If you are a customer trying to make a purchase, please contact the owner of this site. Your transaction has not been processed..."
Generally, this is due to Stripe requiring some additional information about your organization to their account records. This may include making sure that certain details are correct and up to date (e.g. the organisation's address, Tax ID number etc).
At all times, before putting the hold on the account, Stripe will try to contact someone from your organisation via email to obtain the required information. However, sometimes these messages may end up in junk/spam folders without reaching the recipient.