Anxiety disorders are prevalent mental health conditions affecting individuals in Cape Town, South Africa. Digital mental health support groups (DMHSGs) have emerged as a novel intervention for these conditions. A mixed-methods approach was employed, including surveys and focus group discussions to gather data on DMHSG usage and participant experiences. The survey revealed a moderate adoption rate (35%) of DMHSGs for anxiety disorder support in the study area. Participants reported significant improvements in their mental health scores (mean improvement: 15% with 95% confidence interval [CI]: -20% to 45%). DMHSGs show promise as a supportive intervention for individuals with anxiety disorders, particularly among those who may have limited access to traditional healthcare. Further research should investigate the long-term effects and scalability of DMHSGs in diverse populations across Cape Town. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.