To create a many-to-many relationship between two existing custom objects, the administrator needs to create a junction object that has two master-detail relationships, one to each of the custom objects. This will allow each record of one object to be linked to multiple records from another object and vice versa. Reference: https://help.salesforce.com/s/articleView?id=sf.relationships_manytomany.htm&type=5

To make a quick action available on the Salesforce mobile app, you need to add it to the Salesforce Mobile and Lightning Experience Actions section of the page layout. You can use the Page Layout Editor to drag and drop the quick action onto the section.

To show different picklist values for sales and marketing users, you can either use record types or profiles. Record types allow you to have different picklist values for different page layouts assigned to different profiles. Profiles allow you to restrict picklist values based on user permissions.

A validation rule is a tool that allows administrators to enforce data quality and integrity by preventing users from saving records that do not meet certain criteria or conditions. For example, a validation rule can display an error message if a user enters an invalid value in a field. In this case, the administrator can create a validation rule on the account object that displays an error if the account annual revenue field is below 0 or greater than 100 billion. Reference: https://help.salesforce.com/s/articleView?id=sf.validation_rules.htm&type=5

There are two possible reasons why users are unable to access a report based on a custom report type created by an administrator. One is that the custom report type is in development mode, which means that it is not deployed and available for use by other users except for administrators and users with manage custom report types permission. The other is that the report is saved in a private folder, which means that it is visible only to its owner and not shared with other users or groups. Reference: https://help.salesforce.com/s/articleView?id=sf.reports_builder_custom_report_types.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.reports_builder_folders.htm&type=5