Looking for logging into the Jira Plugin For Other Systems site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Jira Plugin For Other Systems site. After that you can login as usual with your login credentials.
https://community.atlassian.com/t5/Marketplace-Apps-questions/Login-User-within-Plugin-Jira-7/qaq-p/99038
https://confluence.atlassian.com/adminjiraserver/using-applinks-to-link-to-other-applications-938846918.html
https://developer.atlassian.com/server/framework/atlassian-sdk/plugin-framework/
https://community.atlassian.com/t5/Answers-Developer-Questions/Best-approach-for-synchronizing-JIRA-with-3rd-Party-System-e-g/qaq-p/529133
https://confluence.atlassian.com/jirakb/unable-to-login-to-jira-applications-596770904.html
https://community.atlassian.com/t5/Answers-Developer-Questions/WebItem-menu-should-appear-after-login-only/qaq-p/518291
https://marketplace.atlassian.com/apps/1213472/secure-login-2fa-jira
https://marketplace.atlassian.com/apps/1214491/secure-login-2fa-confluence
https://confluence.atlassian.com/adminjiraserver/managing-apps-938846929.html
https://community.atlassian.com/t5/Jira-questions/JIRA-MKS-Integrity-Integration/qaq-p/96347
https://developer.atlassian.com/server/framework/atlassian-sdk/set-up-the-atlassian-plugin-sdk-and-build-a-project/
https://community.atlassian.com/t5/Questions/No-more-able-to-login-to-JIRA-via-Google-Chrome-of-my-PC/qaq-p/304011
https://community.atlassian.com/t5/Jira-questions/JIRA-plugin-logging-how/qaq-p/8882