Did you get a serial number? Log into your Magix account, and go to My Account. You should see the download link (which should have been provided in the email sent by Magix after you paid for it) and a serial number to use when you install and run the program for the first time.
A recent "Thank you for your order!" email from MAGIX continues: "If you have not received the confirmation email, please contact our customer support, specifying your order number, under: shop@magix.net"
I did not receive any email from Magix, any order number, any type of number. Nothing. i bought from here: https://www.vegascreativesoftware.com/br/vegas-pro/ My money was not sent back and i cannot use the software.
A correction: the "Thank You" note was not actually an email, but just a note in the Purchasing process to inform that "Ypur order is complete" (with the order number).
@Caitanya I would not include private information in your post.
I've used PayPal in the past. PayPal login will appear if you've selected PayPal and you will have to enter in your information to continue to the payment page. As far as I know, that is the only way for a PayPal payment. I would get a confirmation email from Magix with links and serial numbers.
@Caitanya This is a public user forum, we are not Magix/VEGAS, although Magix/VEGAS staff may occasionally visit.
For security it is advisable not to post any personal information. It could be used by hackers and spammers.
As for your problem it doesn't make sense. As Reyfox has described you would have needed to provide information in order to get to the payment page which is where PayPal gets involved.
You are not unknown to Magix. You already have Magix or Vegas products. This is confirmed by you stating you purchased an upgrade. As you have a registered product you have a Magix account. Go here https://www.magix.com/us/support/my-service-center/ to your Magix account and under My Products look for your recent purchase.