Texture does not fill the figure – OpenGL

Though the viewport coordinates go from negative one to one [-1, 1), texture coordinates go from zero to one [0,1). Therefore three quarters of your viewport are filled with black according to the GL_CLAMP_TO_BORDER policy.

You need to fix your VAO coordinates as follows:

GLfloat vertices[4 * 5]{
      // Positions           // Textures
    -1.0f, -1.0f, 0.0f,     0.0f, 0.0f,
     1.0f, 1.0f, 0.0f,      1.0f, 1.0f,
    -1.0f, 1.0f, 0.0f,      0.0f, 1.0f,
     1.0f, -1.0f, 0.0f,     1.0f, 0.0f
};

EDIT: Also your texture coordinates offset is incorrect. It should be:

// Texture coord
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3*sizeof(float)));

Without the proper offset it is using the X and Y of the position for the texture coordinates.