Check out this Topic: https://www.captainsim.org/forum/csf.pl?num=1541290217

Quote:

Your purchase email address is a part of your order ID and cannot be changed. Q: What should I do if I lost an access to my purchase email address? We are sorry to hear that, but it is customer's responsibility to keep all receipts, order numbers, login information and downloaded products safe and accessible. Due to the nature of download products, if you lose that information you lose access to Your Profile and to Extended Download Service (which we temporarily provide for free). At login page  you can search your Order Number using email address or search your email address using Order Number. If you have lost both, there is nothing we can do, unfortunately. Please note, your account at captainsim.com and your forum account are separate accounts which are not connected in any way.

I'm not sure how you search for your products using your original email, or order number (hopefully you kept a copy of your reciept when you bought the products), but that would be the best way to be able to download new installers for the products you own.
It also looks like you can login using the email address you used when you purchased the products. I just hope you also remember the password you used.