Students won't be able to take assessments with the lockdown browser until the lockdown browser package is installed on students' devices. If your district doesn't use a mobile device manager, students should be able to follow the instructions when taking a locked down assessment, and the package should install just fine.
However, most districts use a mobile device manager of some sort to regulate the software that is allowed on devices. If this is your district, you need to download the package to the device your MDM is on, then load it into your MDM and push it out to all devices from your MDM.
*If you are in need if an .msi file, please reach out to us for further assistance!