Use the NetApp Support portal to find firmware and associated tools.
If this switch runs anything critical (a SAN for a hospital, a backbone for a school), use the search energy to budget for a replacement. You are maintaining a machine that Broadcom legally declared "End of Support" three years ago.
Brocade 300 EZSwitchSetup Administrator's Guide v7.1.0 - Dell brocade ezswitchsetup v710 download 2021
Assign IP addresses, switch names, and administrative credentials.
If your Brocade switch was purchased through NetApp (a common OEM partner), you can sometimes access software through NetApp's support portal. A NetApp knowledge base article details a process where users can go to the NetApp "Download Software" page, search for "Brocade Fibre Channel Switches," and then be redirected to the Broadcom Assist portal. This process requires a valid email domain registered with the device and its serial number. This article explicitly mentions that the procedure applies to obtaining "EZswitchsetup software packages". Use the NetApp Support portal to find firmware
Brocade EZSwitchSetup v7.1.0 on Internet Archive
The setup computer is the machine where the EZSwitchSetup software is installed. The requirements are modest: Brocade 300 EZSwitchSetup Administrator's Guide v7
Disclaimer: Ensure you check the compatibility matrix for your switch model before attempting to use any version of EZSwitchSetup.