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It may not always be possible to directly install the packages using the above links as they will first prompt to login to the required Salesforce Org. If using a sandbox the URL would need to be modified for the test sub domain. With Single Sign On enabled take the path from the URLs above and append it to the URL after logging in . Ee.g. Login login via SSO, then change the URL in the browsers address bar to browsers address bar to something like https://cs13.salesforce.com/packaging/installPackage.apexp?p0=04t900000004pxTxxx where xxx is the p0 parameter in the url above.
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