This can happen for several reasons. Funds may be held by PayPal if your account with them is not verified, or may be in your account as “pending” if your PayPal account has been recently created. Contact PayPal customer service to resolve these issues.
if your MusicDigi account shows you have been paid, but it has not yet shown up in your account. Contact support@musicdigi.com for further assistance after your PayPal account issues have been solved.