See through mesh from all angles

Probably you have one quad per face of the tent right? You either need to duplicate that and flip it, so each side of the tent has 2 faces (in Maya), or use a non-backface-culling shader.

Open that 3d models in 3dsmax and clone the mesh and flip the normal...thats it :)

You need to write Cull Off in the shader, the normals are correct as they are all facing inwards (though outwards would be preferable).

To be extra helpful I've posted a shader below for you ;) it's flat lit but shows what I mean. If you need any specific shader I have a massive collection so I can give you one with the lighting model you need.

 Shader "unityCookie/flat texture no culling" {
     Properties {
         _Color ("Color Tint", Color) = (1.0,1.0,1.0,1.0)
         _MainTex ("Diffuse Texture", 2D) = "white" {}
     }
     SubShader {
         Pass {
             Cull Off
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             
             //user defined variables
             uniform sampler2D _MainTex;
             uniform float4 _MainTex_ST;
             uniform float4 _Color;
             
             //Unity defined Variables
             
             //Base Input Structs
             struct vertexInput{
                 float4 vertex : POSITION;
                 float3 normal : NORMAL;
                 float4 texcoord : TEXCOORD0;
             };
             struct vertexOutput {
                 float4 pos : SV_POSITION;
                 float4 tex : TEXCOORD0;
             };
             
             //vertex function
             vertexOutput vert(vertexInput v){
                 
                 vertexOutput o;
                 
                 o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                 o.tex = v.texcoord;
                 return o;
             }
             
             //fragment function
             float4 frag(vertexOutput i) : COLOR
             {
                 //Lighting
                  
                  
                  //Texture Maps
                  float4 tex = tex2D(_MainTex, _MainTex_ST.xy * i.tex.xy + _MainTex_ST.zw);
                  
                 return float4(tex.rgb * _Color.rgb, 1.0);
             }
             ENDCG
         }
     }
     //fallback commented out during development
     //Fallback "Diffuse"
 }

Save this to a .shader file and it will appear in the material selection menu. I hope this helps!