You can not register using Facebook from the SlideME (SAM) app, but you can register from website using Facebook and use the Facebook email as username to login from SAM.
Visit http://slideme.org/user/register in a web browser to create your account. Once you have an account, you can login with your SlideME username or email and password to access your SlideME account.
Login to the SlideME website, visit My Profile > Edit > Account and you will see a section labeled “Closing account: Click here if you want to close your SlideME account.”
Before trying to reset your password in case of login failure, please assure your device is set to correct date and time. A device with incorrect date set, will be perceived as an "untrusted" device, therefore login will fail.
To retrieve and reset password, go next to the login/register section and you will see "Request new password" or visit the direct link: http://slideme.org/user/password from your web browser.
You will be asked either your email address or username you used to initially register.
Next, an email will be sent to your email address with a link, for you to reset your password to any password of choice. Always assure you make note if you used uppercase or lowercase characters in your password.
If you have not received an email to reset your password, check your spam mailbox. Otherwise it maybe that you entered an incorrect email or your email provider has not relayed the email to you. Assure you whitelist emails from SlideME. Only if problems persist, contact SlideME Support.