The ROM is checking your device model and failing. Fix: Open the ROM ZIP on your PC. Navigate to META-INF/com/google/android/ . Extract updater-script . Delete the first line starting with assert(getprop... ). Save and re-zip.
The is a legacy device (2013) with a Broadcom SoC , not a Qualcomm or Exynos chip. This makes custom ROM development extremely difficult due to closed-source drivers. Unlike popular devices (e.g., Galaxy S2, Nexus 7), the SM-T211 has very limited custom ROM support . custom rom for samsung galaxy tab 3 sm-t211
Since the SM-T211 is the 3G variant of the Tab 3 7.0, you need ROMs specifically compatible with its Marvell PXA986 SoC. The ROM is checking your device model and failing