The Nintendo DS Browser, developed by Opera, required a physical Slot-2 Memory Expansion Pak to function on original DS hardware, while a later version was available via the DSi Shop. Due to modern WPA2/WPA3 security standards and HTTPS certificate requirements, the browser is largely non-functional today and serves as a historical artifact. For an overview of the DSi version, visit Nintendo Support Michael MJD
If you are looking for the "Normal Download Link" for the software, you can find it on several reputable retro-gaming repositories: YouTube·I Dream Of Gaming Nintendo DS Browser On A DSi. Does It Work? Nintendo DS Browser -Normal Download Link-