2024 brushes not compatible?

Were you definitely trying to import them as brushes (.abr) and not another type of preset (shape, gradient, pattern, style).   I hate actually installing presets, because you lose control of the process.  Much better to download the files and place them in the appropriate preset folder.  In fact I go a step further, and keep then in a (Windows) My Documents folder, and place a shortcut to that folder in the preset folder.  This keeps them safe from major update issues (we get a lot of posts fropm people who have lost the brush presets after an update) and makes it easier to share one set of presets between the Release and Beta versions.

https://helpx.adobe.com/nz/photoshop/kb/preference-file-names-locations-photoshop.html

Just tried the Spring 2024 brushes in Photoshop 2025 as well as 2019, just to make sure there were no compatibility issues. The .ABR format should work across most any version of Photoshop. Make sure the files size is right (22,475 kb for this particular one) because if the file failed to download properly, that could lead to this error. Also, make sure you didn't rename the file so that it lost the .ABR extension, otherwise Photoshop will assume it is an image file and give you an error. Also, how are you attempting to import the brushes? There are a few different ways and I want to make sure I'm testing the way you are. 

How are you loading the Brushes into Photoshop?

With the Spring 2024 Brushes i had success both just dropping the Spring-Brushes-2024.abr into the Photoshop 2025 shortcut in the Dock and using Import Brushes from the Brush Picker fly out menu.

This is with Photoshop 2025 (ps ver 26.3) running macOS Sequoia 15.3.1 on a 2022 Mac Studio.

@turner111 I just tested downloading some of the brushes, and they're installing fine for me, Photoshop version 26.3 on Windows 11