When a Jira automation rule doesn't run, check the rule's audit log first — it tells you whether the rule fired at all, fired and was filtered out by a condition, or failed with an error. From there the usual causes are: the rule is disabled, its scope is wrong, the trigger doesn't match, a condition is filtering everything, the actor lacks permission, or you've hit your plan's execution limit.
A scheduled Jira automation that sends one email per issue is almost always caused by putting JQL in the scheduled trigger itself. When the trigger matches issues directly, the rule runs once per matched issue. Move the JQL into a Lookup Issues action, leave the trigger's JQL empty, and loop over the results in a single email.
A Jira link only works for someone with an Atlassian account, access to your site, and browse permission on that project. External people have none of those by default, so they hit a login wall or a 'you don't have permission' error. The options are to license them, use guest access on a paid plan, or send the information rather than the link.
If everyone in your company can see your Jira project, it's almost always because the Browse Projects permission is granted to 'Any logged-in user' in the project's permission scheme. That default makes the project visible to every licensed user in your site. Change that grant to a specific project role or group and the exposure stops.