Wireless USB Adapters: If you need Wi-Fi on an older Mac, a USB dongle with dedicated Mac support (like those from TP-Link or BearExtender) is more reliable than trying to force a DWA-525 to work.
The DWA-525 typically uses the Ralink RT3060 or RT5360 chipset. Since MediaTek acquired Ralink, you can sometimes find legacy "RT2860" or "RT3000" series drivers that include support for these chips on older versions of Mac OS X. Wireless Dwa 525 Drivers For Mac