The Herzum Attachments Manager is an add-on for Atlassian JIRA that let you define, at project level, the maximum number of attachments per issue and also overwrite the default JIRA maximum attachment size per project (JIRA Attachment size).
Preconditions
Ensure that overall JIRA Attachment settings have been configured to allow attachments.
This guide provides information on configuring your setup via the HAM add-on configuration screen.